U.S. patent number 8,787,142 [Application Number 13/063,841] was granted by the patent office on 2014-07-22 for transmission and reception of a wideband signal with narrowband interference.
This patent grant is currently assigned to Nokia Siemens Networks Oy. The grantee listed for this patent is Oliver Cyranka, Martin Goldberg, Helmut Heinz, Rupert Herzog, Thomas Hindelang, Sabine Roessel, Wolfgang Zirwas. Invention is credited to Oliver Cyranka, Martin Goldberg, Helmut Heinz, Rupert Herzog, Thomas Hindelang, Sabine Roessel, Wolfgang Zirwas.
United States Patent |
8,787,142 |
Cyranka , et al. |
July 22, 2014 |
Transmission and reception of a wideband signal with narrowband
interference
Abstract
It is disclosed a method including accommodating, in frequency
domain, a first bandwidth of a first carrier signal with respect to
a second bandwidth of a second carrier signal such that the first
bandwidth adjoins to or overlaps the second bandwidth, the first
bandwidth being greater than the second bandwidth. In a further
aspect, prior to the transmission, the interference of the
modulated second carrier signal is subtracted from each of the
plurality of subcarrier signals of the first carrier signal.
Inventors: |
Cyranka; Oliver (Munchen,
DE), Goldberg; Martin (Greifenberg, DE),
Heinz; Helmut (Turkheim, DE), Herzog; Rupert (Bad
Aibling, DE), Hindelang; Thomas (Furstenfeldbruck,
DE), Roessel; Sabine (Munchen, DE), Zirwas;
Wolfgang (Munchen, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Cyranka; Oliver
Goldberg; Martin
Heinz; Helmut
Herzog; Rupert
Hindelang; Thomas
Roessel; Sabine
Zirwas; Wolfgang |
Munchen
Greifenberg
Turkheim
Bad Aibling
Furstenfeldbruck
Munchen
Munchen |
N/A
N/A
N/A
N/A
N/A
N/A
N/A |
DE
DE
DE
DE
DE
DE
DE |
|
|
Assignee: |
Nokia Siemens Networks Oy
(Espoo, FI)
|
Family
ID: |
42005558 |
Appl.
No.: |
13/063,841 |
Filed: |
September 15, 2009 |
PCT
Filed: |
September 15, 2009 |
PCT No.: |
PCT/EP2009/061893 |
371(c)(1),(2),(4) Date: |
May 23, 2011 |
PCT
Pub. No.: |
WO2010/029177 |
PCT
Pub. Date: |
March 18, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110222479 A1 |
Sep 15, 2011 |
|
Foreign Application Priority Data
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|
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Sep 15, 2008 [EP] |
|
|
08164354 |
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Current U.S.
Class: |
370/204;
455/63.1; 375/350; 455/296; 375/346; 370/203 |
Current CPC
Class: |
H04L
27/2647 (20130101); H04J 11/004 (20130101); H04L
27/2626 (20130101); H04W 16/14 (20130101); H04L
5/0066 (20130101); H04W 84/042 (20130101) |
Current International
Class: |
H04J
9/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1 217 733 |
|
Jun 2002 |
|
EP |
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1 798 924 |
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Jun 2007 |
|
EP |
|
1959625 |
|
Aug 2008 |
|
EP |
|
WO 95/20277 |
|
Jul 1995 |
|
WO |
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WO 99/38270 |
|
Jul 1999 |
|
WO |
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WO 2008/088254 |
|
Jul 2008 |
|
WO |
|
Other References
Zhang, D., et al., "A novel narrowband interference canceller for
OFDM systems",(2004), (pp. 1426-1430). cited by applicant .
R1-082438, 3GPP TSG RAN WG1 #53bis, "Efficient Utilization of
Unused PUCCH RB" LG Electronics Inc., Warsaw, Poland, Jun. 30-Jul.
4, 2008, 3 pgs. cited by applicant .
Zhang, D., et al., "A novel narrowband interference canceller for
OFDM systems", abstract only, Mar. 21-25, 2004, 1 page. cited by
applicant.
|
Primary Examiner: Mills; Donald
Attorney, Agent or Firm: Harrington & Smith
Claims
The invention claimed is:
1. A method, comprising: retrieving a first carrier signal from a
received transmission signal comprising a plurality of subcarrier
signals of the first carrier signal, each of which subcarrier
signals being interfered by an effective interference of a
modulated second carrier signal wherein the retrieving is performed
by subtracting a generated replica of the second carrier signal
from the received transmission signal; prior to the subtracting,
generating the replica of the second carrier signal by:
demodulating the decoded transmission signal; decoding the received
transmission signal; and filtering the demodulated and decoded
transmission signal for removing the subcarrier signals overlapping
the modulated second carrier signal in bandwidth.
2. The method according to claim 1, further comprising, prior to
the retrieving, receiving the transmission signal.
3. The method according to claim 1, wherein the retrieving further
comprises, after the subtracting, transforming a signal resulting
from the subtracting from a time domain into a frequency
domain.
4. The method according to claim 2, further comprising, after the
receiving and prior to the retrieving, queuing the received
transmission signal.
5. The method according to claim 1, wherein the retrieving is
performed by: decoding the received transmission signal; filtering
the decoded transmission signal for removing the subcarrier signals
overlapping the modulated second carrier signal in bandwidth;
detecting a midamble in at least one signal burst of the second
carrier signal based on a reference midamble; extracting the
midamble from the current signal burst; estimating current channel
information from the extracted midamble; and processing symbols
sent via the first carrier signal based on the estimated current
channel information during a subsequent burst of the second carrier
signal after the at least one burst.
6. The method according to claim 3, wherein at least one of the
following applies: the first carrier signal is a long term
evolution carrier signal; the second carrier signal is a global
system for mobile communications carrier signal; the transforming
from time domain into frequency domain is one of a Fourier
transformation and a fast Fourier transformation; the transforming
from frequency domain into time domain is one of an inverse Fourier
transformation and an inverse fast Fourier transformation; the
timing information is an orthogonal frequency division multiplexing
guard interval; the channel information is channel state
information; and the queuing is performed based on a first in first
out queue.
7. The apparatus according to claim 1, further comprising means for
receiving the transmission signal prior to the retrieving performed
by the means for retrieving.
8. The method according to claim 1 performed with a non-transitory
computer readable medium storing a computer program product, the
computer program product executed by a processor.
9. The method according to claim 1, wherein the first carrier
signal and the second carrier signal are communicated using
different access technologies.
10. The method according to claim 1, wherein the first carrier
signal and the second carrier signal are transmitted from a single
antenna or from multiple different antenna, respectively, for
transmitting.
11. The method according to claim 1, wherein the first carrier
signal and the second carrier signal are transmitted in a first
bandwidth and a second bandwidth, respectively, and the first
bandwidth adjoins to or overlaps the second bandwidth.
12. An apparatus, comprising: means for retrieving a first carrier
signal from a received transmission signal comprising a plurality
of subcarrier signals of the first carrier signal each of which
subcarrier signals being interfered by an effective interference of
a modulated second carrier signal, wherein the means for retrieving
further comprises means for subtracting a generated replica of the
second carrier signal from the received transmission signal; means
for generating, prior to the subtracting performed by the means for
subtracting, the replica of the second carrier signal, the means
for generating comprising: means for demodulating the decoded
transmission signal; means for decoding the received transmission
signal; and means for filtering the demodulated and decoded
transmission signal for removing the subcarrier signals overlapping
the modulated second carrier signal in bandwidth.
13. An apparatus comprising: at least one processor; and at least
one memory including computer program code, where the at least one
memory and the computer program code are configured, with the at
least one processor, to cause the apparatus to at least: retrieve a
first carrier signal from a received transmission signal comprising
a plurality of subcarrier signals of the first carrier signal, each
of which subcarrier signals being interfered by an effective
interference of a modulated second carrier signal wherein the
retrieving is performed by subtracting a generated replica of the
second carrier signal from the received transmission signal; prior
to the subtracting, generate the replica of the second carrier
signal by: demodulating the decoded transmission signal; decoding
the received transmission signal; and filtering the demodulated and
decoded transmission signal for removing the subcarrier signals
overlapping the modulated second carrier signal in bandwidth.
14. The apparatus according to claim 13, wherein the first carrier
signal and the second carrier signal are communicated using
different access technologies.
15. The apparatus according to claim 13, wherein the first carrier
signal and the second carrier signal are transmitted from a single
antenna or from multiple different antenna, respectively, for
transmitting.
16. The apparatus according to claim 13, wherein the first carrier
signal and the second carrier signal are transmitted in a first
bandwidth and a second bandwidth, respectively, and the first
bandwidth adjoins to or overlaps the second bandwidth.
17. The apparatus according to claim 13 embodied in a base station
or a user equipment.
18. The apparatus according to claim 13, wherein the at least one
memory including the computer program code is configured with the
at least one processor to cause the apparatus to, after the
subtracting, transform a signal resulting from the subtracting from
a time domain into a frequency domain.
Description
FIELD OF THE INVENTION
The present invention relates to signal transmission and reception.
More specifically, the present invention relates to methods,
apparatuses, a system and a related computer program product for
signal transmission and receptions. Examples of the present
invention may be applicable e.g. to cellular systems such as 3GPP
(3.sup.rd generation partnership project) LTE (long term
evolution).
BACKGROUND
Currently, extensions to the LTE Release 8 standard are discussed
for future releases, like LTE Release 9 or IMT (international
mobile telephony) advanced/LTE-Advanced, e.g. in order to increase
system performance.
At the same time, there may be different application scenarios for
LTE systems in different frequency bands. Specifically, the tight
cooperation of LTE with GSM (global system for mobile
communications) transmissions may be considered as such a
cooperation allows for providing full coverage GSM systems in
combination with high performance LTE radio air interfaces.
For example, as the minimum LTE bandwidth may be 1.4 MHz in a
system, it will be difficult to accommodate e.g. an additional GSM
carrier of 200 KHz bandwidth in this same frequency band of 1.6
MHz, as there will be strong frequency guard bands required to
avoid inter system interference.
However, if a GSM carrier and an LTE carrier are used in close-by
frequency bands or even in the same frequency band, there may be
strong interference due to mutual out-of-band emissions. As GSM has
a much smaller bandwidth of only 200 KHz compared to e.g. 10 or 20
MHz for LTE, the main interference may stem from GSM to the LTE
system under the assumption that both carriers have substantially
the same overall transmit power.
In consideration of the above, it is an object of examples of the
present invention to overcome one or more of the above drawbacks.
In particular, the present invention provides methods, apparatuses,
a system and a related computer program product for signal
transmission and reception.
According to an example of the present invention, in a first
aspect, this object is for example achieved by a method
comprising:
accommodating, in frequency domain, a first bandwidth of a first
carrier signal with respect to a second bandwidth of a second
carrier signal such that the first bandwidth adjoins to or overlaps
the second bandwidth, the first bandwidth being greater than the
second bandwidth.
According to further refinements of the example of the present
invention as defined under the above first aspect,
the method further comprises transmitting the first and second
signals from a single means for transmitting;
the method further comprises transmitting the first and second
signals from a plurality of means for transmitting in a coordinated
manner.
According to an example of the present invention, in a second
aspect, this object is for example achieved by a method
comprising:
transmitting a transmission signal comprising a plurality of
subcarrier signals of a first carrier signal, each of which
subcarrier signals being subtracted by an effective interference of
a modulated second carrier signal.
According to further refinements of the example of the present
invention as defined under the above second aspect,
the method further comprises, prior to the transmitting,
subtracting the effective interference of the modulated second
carrier signal from each of the plurality of subcarrier signals of
the first carrier signal;
the method further comprises, prior to the transmitting, filtering
the modulated second carrier signal for removing the subcarrier
signals overlapping the modulated second carrier signal in
bandwidth;
the method further comprises, after the subtracting and prior to
the transmitting transforming a result signal resulting from the
subtracting from frequency domain into time domain, inserting time
intervals into the transformed result signal, and combining the
result signal being transformed and inserted with time intervals
with the filtered and modulated second carrier signal to form the
transmission signal;
the method further comprises, after the filtering and prior to the
subtracting, transforming the modulated first carrier signal from
time domain into frequency domain;
the method further comprises, after the transforming, calculating,
by filtering the transformed and modulated second carrier signal, a
resulting distortion from the second carrier signal to the first
carrier signal based on at least one of timing information and
channel information.
According to an example of the present invention, in a third
aspect, this object is for example achieved by a method
comprising:
retrieving a first carrier signal from a received transmission
signal comprising a plurality of subcarrier signals of the first
carrier signal, each of which subcarrier signals being interfered
by an effective interference of a modulated second carrier
signal.
According to further refinements of the example of the present
invention as defined under the above third aspect,
the method further comprises, prior to the retrieving, receiving
the transmission signal;
the retrieving is performed by subtracting a generated replica of
the second carrier signal from the received transmission
signal;
the method further comprises, prior to the subtracting, generating
the replica of the second carrier signal by demodulating the
decoded transmission signal, decoding the received transmission
signal, and filtering the demodulated and decoded transmission
signal for removing the subcarrier signals overlapping the
modulated second carrier signal in bandwidth;
the retrieving further comprises, after the subtracting,
transforming a signal resulting from the subtracting from time
domain into frequency domain;
the method further comprises, after the receiving and prior to the
retrieving, queuing the received transmission signal;
the retrieving is performed by decoding the received transmission
signal, filtering the decoded transmission signal for removing the
subcarrier signals overlapping the modulated second carrier signal
in bandwidth, detecting a midamble in at least one signal burst of
the second carrier signal based on a reference midamble, extracting
the midamble from the current signal burst, estimating current
channel information from the extracted midamble, and processing
symbols sent via the first carrier signal based on the estimated
current channel information during a subsequent burst of the second
carrier signal after the at least one burst.
According to an example of the present invention, in a fourth
aspect, this object is for example achieved by a method
comprising:
distributing, in unoccupied control channel elements of a first
carrier signal having a first bandwidth, at least a portion of a
second carrier signal having a second bandwidth by using different
control channel configurations in at least one neighboring cell,
the first bandwidth being greater than the second bandwidth.
According to further refinements of the example of the present
invention as defined under the above first to fourth aspects,
the first carrier signal is a long term evolution carrier
signal;
the second carrier signal is a global system for mobile
communications carrier signal;
the transforming from time domain into frequency domain is one of a
Fourier transformation and a fast Fourier transformation;
the transforming from frequency domain into time domain is one of
an inverse Fourier transformation and an inverse fast Fourier
transformation;
the timing information is an orthogonal frequency division
multiplexing guard interval;
the channel information is channel state information;
the queuing is performed based on a first in first out queue.
According to an example of the present invention, in a fifth
aspect, this object is for example achieved by an apparatus
comprising:
means for accommodating, in frequency domain, a first bandwidth of
a first carrier signal with respect to a second bandwidth of a
second carrier signal, the first bandwidth adjoining to or
overlapping the second bandwidth, and the first bandwidth being
greater than the second bandwidth.
According to further refinements of the example of the present
invention as defined under the above fifth aspect,
the apparatus further comprises a single means for transmitting the
first and second signals;
the apparatus further comprises a plurality of means for
transmitting the first and second signals in a coordinated
manner;
the or each means for transmitting is constituted by a radio
frequency, power amplifier and antenna chain.
According to an example of the present invention, in a sixth
aspect, this object is for example achieved by an apparatus
comprising:
means for transmitting a transmission signal comprising a plurality
of subcarrier signals of a first carrier signal, each of which
subcarrier signals being subtracted by an effective interference of
a modulated second carrier signal.
According to further refinements of the example of the present
invention as defined under the above sixth aspect,
the apparatus further comprises means for subtracting, prior to the
transmitting performed by the means for transmitting, the effective
interference of the modulated second carrier signal from each of
the plurality of subcarrier signals of the first carrier
signal;
the apparatus further comprises means for filtering, prior to the
transmitting performed by the means for transmitting, the modulated
second carrier signal for removing the subcarrier signals
overlapping the modulated second carrier signal in bandwidth;
the apparatus further comprises means for transforming, after the
subtracting performed by the means for subtracting and prior to the
transmitting performed by the means for transmitting, a result
signal resulting from the subtracting from frequency domain into
time domain, means for inserting, after the subtracting performed
by the means for subtracting and prior to the transmitting
performed by the means for transmitting, time intervals into the
transformed result signal, and means for combining, after the
subtracting performed by the means for subtracting and prior to the
transmitting performed by the means for transmitting, the result
signal being transformed and inserted with time intervals with the
filtered and modulated second carrier signal to form the
transmission signal;
the apparatus further comprises means for transforming, after the
filtering performed by the means for filtering and prior to the
subtracting performed by the means for subtracting, the modulated
first carrier signal from time domain into frequency domain;
the apparatus further comprises means for calculating, after the
transforming performed by the means for transforming and by
filtering the transformed and modulated second carrier signal, a
resulting distortion from the second carrier signal to the first
carrier signal based on at least one of timing information and
channel information.
According to an example of the present invention, in a seventh
aspect, this object is for example achieved by an apparatus
comprising:
means for retrieving a first carrier signal from a received
transmission signal comprising a plurality of subcarrier signals of
the first carrier signal, each of which subcarrier signals being
interfered by an effective interference of a modulated second
carrier signal.
According to further refinements of the example of the present
invention as defined under the above seventh aspect,
the apparatus further comprises means for receiving the
transmission signal prior to the retrieving performed by the means
for retrieving;
the means for retrieving further comprises means for subtracting a
generated replica of the second carrier signal from the received
transmission signal;
the apparatus further comprises means for generating, prior to the
subtracting performed by the means for subtracting, the replica of
the second carrier signal, the means for generating comprising
means for demodulating the decoded transmission signal, means for
decoding the received transmission signal, and means for filtering
the demodulated and decoded transmission signal for removing the
subcarrier signals overlapping the modulated second carrier signal
in bandwidth;
the means for retrieving further comprises means for transforming,
after the subtracting performed by the means for subtracting, a
signal output by the means for subtracting from time domain into
frequency domain;
the apparatus further comprises means for queuing the received
transmission signal after the receiving performed by the means for
receiving and prior to the retrieving performed by the means for
retrieving;
the means for retrieving comprises means for decoding the received
transmission signal, means for filtering the decoded transmission
signal for removing the subcarrier signals overlapping the
modulated second carrier signal in bandwidth, means for detecting a
midamble in at least one signal burst of the second carrier signal
based on a reference midamble, means for extracting the midamble
from the current signal burst, means for estimating current channel
information from the extracted midamble, and means for processing
symbols sent via the first carrier signal based on the estimated
current channel information during a subsequent burst of the second
carrier signal after the at least one burst.
According to an example of the present invention, in an eighth
aspect, this object is for example achieved by an apparatus
comprising:
means for distributing, in unoccupied control channel elements of a
first carrier signal having a first bandwidth, at least a portion
of a second carrier signal having a second bandwidth by using
different control channel configurations in at least one
neighboring cell, the first bandwidth being greater than the second
bandwidth.
According to further refinements of the example of the present
invention as defined under the above fifth to eighth aspects,
the first carrier signal is a long term evolution carrier
signal;
the second carrier signal is a global system for mobile
communications carrier signal;
the transforming from time domain into frequency domain is one of a
Fourier transformation and a fast Fourier transformation;
the transforming from frequency domain into time domain is one of
an inverse Fourier transformation and an inverse fast Fourier
transformation;
the timing information is an orthogonal frequency division
multiplexing guard interval;
the channel information is channel state information;
the means for queuing is configured to queue based on a first in
first out queue;
at least one, or more of means for accommodating, means for
transmitting, means for subtracting, means for filtering, means for
calculating, means for combining, means for transforming, means for
inserting, means for retrieving, means for receiving, means for
generating, means for queuing, means for modulating, means for
demodulating, means for decoding, means for detecting, means for
extracting, means for estimating, means for processing, means for
distributing and the apparatus is implemented as a chipset or
module.
According to an example of the present invention, in a ninth
aspect, this object is for example achieved by a system
comprising:
a transmission apparatus according to the above sixth aspect;
an accommodating apparatus according to the above fifth aspect;
a receiving apparatus according to the above seventh aspect;
and
a distributing apparatus according to the above eighth aspect.
According to an example of the present invention, in a tenth
aspect, this object is for example achieved by a computer program
product comprising code means for performing method steps of a
method according to any one of the above first to fourth aspects,
when run on a processing means or module.
In this connection, it has to be pointed out that examples of the
present invention enable one or more of the following:
Alleviating a need for separation of the LTE spectrum into two or
more different LTE carriers;
Alleviating a need for insertion of rather large (frequency) guard
bands to separate LTE and GSM systems from each other;
Enhancing overall spectral efficiency of the system concept;
Complying with a legacy GSM receiver, since the interference due to
the LTE signal is mainly blocked due to according receiver filters,
and since the residual LTE out of band interference is very
small;
Providing full GSM coverage;
Effectively combining LTE and GSM signals, such that specifically
GSM might be included into the LTE signal at an arbitrary place of
the spectrum, e.g. at suitable positions for reducing the
interference on control channels.
Allowing support of UEs (user equipments) by pre-coding, which UEs
are not aware of the combined LTE-GSM transmission. This may be
facilitated by CSI (channel state information) that may be
available;
Enabling interference cancellation in the UEs e.g. by implementing
a GSM decoder. Additionally, corresponding control signals and
messages are defined e.g. for broadcasting of the location of the
GSM carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
Examples of the present invention are described herein below with
reference to the accompanying drawings, in which:
FIG. 1 shows methods according to an example of the present
invention for signal transmission and reception;
FIG. 2 shows an alternative method according to an example of the
present invention for signal transmission and reception;
FIG. 3 shows an apparatus according to an example of the present
invention for accommodating e.g. a GSM carrier signal into an LTE
carrier signal using e.g. mutual interference between the GSM and
LTE carriers;
FIG. 4 shows an apparatus according to an example of the present
invention for transmitting using e.g. pre-compensated combined
GSM-LTE signal generation;
FIG. 5 shows resulting interference e.g. from GMSK (Gaussian
minimum shift keying) to an LTE OFDM signal according to the
apparatus shown in FIG. 4;
FIG. 6 shows an apparatus according to an example of the present
invention for receiving and retrieving using e.g. a time domain
approach for combined GSM and LTE transmission;
FIG. 7 shows an alternative apparatus according to an example of
the present invention for receiving and retrieving using e.g. CSI
based cancellation of GSM interferer(s);
FIG. 8 shows a delay reduction according to the apparatus shown in
FIG. 7; and
FIG. 9 shows an alternative method and apparatus according to an
example of the present invention using e.g. prohibited and
available narrowband embedding regions aligned with respect to UL
(uplink) and DL (downlink).
DETAILED DESCRIPTION OF THE PRESENT INVENTION
Examples of the present invention are described herein below by way
of example with reference to the accompanying drawings.
It is to be noted that for this description, the terms "long term
evolution carrier signal; global system for mobile communications
carrier signal; (fast) Fourier transformation; inverse (fast)
Fourier transformation; orthogonal frequency division multiplexing
guard interval; channel state information; and first in first out
queue" are examples for "first carrier signal; second carrier
signal; transforming from time domain into frequency domain;
transforming from frequency domain into time domain; timing
information; the channel information; and queuing", respectively,
without restricting the latter-named terms to the special technical
or implementation details imposed to the first-named terms.
FIGS. 1 and 2 show methods for signal transmission and reception
according to an example of the present invention. Signaling between
elements is indicated in horizontal direction, while time aspects
between signaling may be reflected in the vertical arrangement of
the signaling sequence as well as in the sequence numbers. It is to
be noted that the time aspects indicated in FIGS. 1 and 2 do not
necessarily restrict any one of the method steps shown to the step
sequence outlined. This applies in particular to method steps that
are functionally disjunctive with each other. Within FIGS. 1 and 2,
for ease of description, means or portions which may provide main
functionalities are depicted with solid functional blocks or arrows
and/or a normal font, while means or portions which may provide
optional functions are depicted with dashed functional blocks or
arrows and/or an italic font.
As shown in FIGS. 1 and 2, a communication system 200 may comprise
a transmitter 201 according to an example of the present invention
(such as a BS (base station)), a receiver 202 (such as a UE)
according to an example of the present invention, a transmitter
201' (see also FIG. 6) and a receiver 202'.
In an optional step S1-0, e.g. the transmitter 201 filtering a
modulated second carrier signal for removing subcarrier signals
overlapping the modulated second carrier signal in bandwidth.
In an optional step S1-1, e.g. the transmitter 201 may perform
transforming the modulated first carrier signal from time domain
into frequency domain (e.g. by a (F)FT).
In a further optional step S1-2, e.g. the transmitter 201 may
perform calculating, e.g. by filtering the transformed and
modulated second carrier signal, a resulting distortion from the
second carrier signal to the first carrier signal based on at least
one of timing information (e.g. OFDM GI) and channel information
(e.g. CSI).
In an optional step S1-3, e.g. the transmitter 201 may perform
subtracting the effective interference of the modulated second
carrier signal from each of the plurality of subcarrier signals of
the first carrier signal.
Then, in optional steps S1-4a to S1-4c, e.g. the transmitter 201
may perform transforming a result signal resulting from the
subtracting from frequency domain into time domain (IFFT),
inserting time intervals into the transformed result signal; and
combining the result signal being transformed and inserted with
time intervals with the filtered and modulated second carrier
signal to form the transmission signal.
In step S1-5, e.g. the transmitter 201 may perform transmitting the
transmission signal comprising a plurality of the subcarrier
signals of the first carrier signal (LTE), each of which subcarrier
signals being subtracted by the effective interference of the
modulated second carrier signal (GMSK).
Alternatively, in step S2-0, e.g. an accommodator (or means for
accommodating) 203 shown in FIG. 3 (described in more detail herein
below) may perform accommodating (S2-0), in frequency domain, a
first bandwidth of a first carrier signal (LTE carrier) with
respect to a second bandwidth of a second carrier signal (GSM
carrier) such that the first bandwidth adjoins to or overlaps the
second bandwidth, the first bandwidth being greater than the second
bandwidth.
E.g. in case the transmission signal from the transmitter 201' has
a form given by the accommodator, in an optional step S3-0, e.g.
the receiver 202 may perform receiving a transmission signal
comprising a plurality of subcarrier signals of the first carrier
signal, each of which subcarrier signals being interfered by an
effective interference of a modulated second carrier signal
(GMSK).
Then, in an optional step S3-1, e.g. the receiver 202 may perform
queuing the received transmission signal.
Thus, in step S3-2, e.g. the receiver 202 may perform retrieving
the first carrier signal (e.g. LTE) from the received transmission
signal.
Then, in an optional step S3-3, e.g. the receiver 202 may perform
generating a replica of the second carrier signal. The generating
performed may comprise, in optional steps S3-4a to S3-4c,
demodulating (S3-4a) the received transmission signal; decoding the
demodulated transmission signal, and filtering the demodulated and
decoded transmission signal for removing the subcarrier signals
overlapping the modulated second carrier signal in bandwidth.
Then, in an optional step S3-5, e.g. the receiver 202 may perform
subtracting the generated replica of the second carrier signal from
the received transmission signal.
Finally, in an optional step S3-6, e.g. the receiver may perform
transforming the signal resulting from the subtracting from time
domain into frequency domain.
Alternatively, as shown in FIG. 2, the receiver 202 may also
perform the retrieving by performing, in optional steps S3-2a to
S3-2f, decoding the received transmission signal, filtering the
decoded transmission signal for removing the subcarrier signals
overlapping the modulated second carrier signal in bandwidth,
detecting a midamble in at least one signal burst of the second
carrier signal based on a reference midamble, extracting the
midamble from the current signal burst, estimating current channel
information from the extracted midamble; and processing symbols
sent via the first carrier signal based on the estimated current
channel information during a subsequent burst of the second carrier
signal after the at least one burst.
Finally, as shown in FIG. 9, another example of the present
invention may also cover distributing, in unoccupied control
channel elements of the first carrier signal having the first
bandwidth, at least a portion of the second carrier signal having
the second bandwidth by using different control channel
configurations in at least one neighboring cell, the first
bandwidth being greater than the second bandwidth.
As for further refinements of the methods according to an example
of the present invention, the first carrier signal may be a long
term evolution carrier signal, and the second carrier signal may be
a global system for mobile communications carrier signal. In
addition, the transforming from time domain into frequency domain
may be a (fast) Fourier transformation, and the transforming from
frequency domain into time domain may be an inverse (fast) Fourier
transformation. Still further, the timing information may an
orthogonal frequency division multiplexing guard interval, and the
channel information may channel state information. Moreover, the
queuing may be performed based on a first in first out queue.
Finally, the transmitting of the first and second signals may be
from a single means for transmitting or from a plurality of means
for transmitting in a coordinated manner.
FIGS. 3 to 8 show apparatuses (e.g. transmitter 201, transmitter
201', receiver 202 and accommodator 203) for signal transmission
and reception according to an example and an alternative example of
the present invention. Within those Figs, for ease of description,
means or portions which may provide main functionalities are
depicted with solid functional blocks or arrows and a normal font,
while means or portions which may provide optional functions are
depicted with dashed functional blocks or arrows and an italic
font.
The transmitter 201 may comprise a transmitting antenna (or means
for transmitting) 2011, a modulator (or means for modulating) 2012,
a low-pass filter (or means for filtering) 2013, a transformer (or
means for transforming) 2014, an SC filter for calculating (or
means for calculating) 2015, an inverse transformer (or means for
transforming) 2016, an inserter (or means for inserting) 2017, a
combiner (or means for combining) 2018 and a subtractor (or means
for subtracting) 2019.
The receiver 202 may comprise a retriever (or means for retrieving)
2021, a generator (or means for generating) 2022, a receiving
antenna (or means for receiving) 2023, a demodulator (or means for
demodulating) 2024, a modulator (or means for modulating) 2025, a
low-pass filter (or means for filtering) 2026, a FIFO (or means for
queuing) 2027, a subtractor (or means for subtracting) 2028 and a
transformer (or means for transforming) 2029.
Optionally, e.g. the means for filtering 2013 of the transmitter
201 may perform filtering a modulated second carrier signal for
removing subcarrier signals overlapping the modulated second
carrier signal in bandwidth.
Also optionally, e.g. the means for transforming 2014 of the
transmitter 201 may perform transforming the modulated first
carrier signal from time domain into frequency domain (e.g. by a
(F)FT).
Optionally, e.g. the means for calculating 2015 of the transmitter
201 may perform calculating, e.g. by filtering the transformed and
modulated second carrier signal, a resulting distortion from the
second carrier signal to the first carrier signal based on at least
one of timing information (e.g. OFDM GI) and channel information
(e.g. CSI).
Optionally, e.g. the means for subtracting 2019 of the transmitter
201 may perform subtracting the effective interference of the
modulated second carrier signal from each of the plurality of
subcarrier signals of the first carrier signal.
Then, e.g. the means for transforming 2016 of the transmitter 201
may perform transforming a result signal resulting from the
subtracting from frequency domain into time domain (IFFT), e.g. the
means for inserting 2017 of the transmitter 201 may perform
inserting time intervals into the transformed result signal, and
e.g. the means for combining 2018 of the transmitter 201 may
perform combining the result signal being transformed and inserted
with time intervals with the filtered and modulated second carrier
signal to form the transmission signal.
Then, e.g. the means for transmitting 2011 of the transmitter 201
may perform transmitting the transmission signal comprising a
plurality of the subcarrier signals of the first carrier signal
(LTE), each of which subcarrier signals being subtracted by the
effective interference of the modulated second carrier signal
(GMSK).
Alternatively, as shown in FIGS. 3 and 6, e.g. an accommodator (or
means for accommodating) 203 may perform accommodating, in
frequency domain, a first bandwidth of a first carrier signal (e.g.
LTE carrier) with respect to a second bandwidth of a second carrier
signal (e.g. GSM carrier) such that the first bandwidth adjoins to
or overlaps the second bandwidth, the first bandwidth being greater
than the second bandwidth. As shown in FIG. 3, in a case i), the
second carrier signal (e.g. LTE signal carrier) may fully overlap
the second carrier signal (e.g. GSM carrier); in a case ii), the
second signal may overlap the first signal partially; and in a case
iii), the second signal may adjoin to the first signal.
Optionally, e.g. in case the transmission signal from the
transmitter 201' has a form given by the accommodator 203, e.g. the
means for receiving 2023 of the receiver 202 may perform receiving
a transmission signal comprising a plurality of subcarrier signals
of the first carrier signal, each of which subcarrier signals being
interfered by an effective interference of a modulated second
carrier signal (GMSK).
Then optionally, e.g. the means for queuing 2027 of the receiver
202 may perform queuing the received transmission signal.
Thus, e.g. the means for retrieving 2021 of the receiver 202 may
perform retrieving the first carrier signal (e.g. LTE) from the
received interfered transmission signal.
Optionally, e.g. the means for generating 2022 of the means for
retrieving 2022 may perform generating a replica of the second
carrier signal. The means for generating 2022 may optionally
comprise means for demodulating 2024 the received transmission
signal, means for decoding 2025 the demodulated transmission
signal, and means for filtering 2026 the demodulated and decoded
transmission signal for removing the subcarrier signals overlapping
the modulated second carrier signal in bandwidth.
Then, e.g. the optional means for subtracting 2028 of the means for
retrieving 2021 may perform subtracting the generated replica of
the second carrier signal from the received transmission
signal.
Finally, e.g. the optional means for transforming 2029 of the
receiver 202 may perform transforming the signal resulting from the
subtracting from time domain into frequency domain.
Alternatively, as shown in FIG. 7, the means for retrieving of the
receiver 202 may also comprise means for decoding 2021a the
received transmission signal, means for filtering 2021b the decoded
transmission signal for removing the subcarrier signals overlapping
the modulated second carrier signal in bandwidth, means for
detecting 2021c a midamble in at least one signal burst of the
second carrier signal based on a reference midamble, means for
extracting 2021d the midamble from the current signal burst, means
for estimating 2021e current channel information from the extracted
midamble; and means for processing 2021f symbols sent via the first
carrier signal based on the estimated current channel information
during a subsequent burst of the second carrier signal after the at
least one burst.
Finally, as shown in FIG. 9, another example of the present
invention may also cover means for distributing, in unoccupied
control channel elements of the first carrier signal having the
first bandwidth, at least a portion of the second carrier signal
having the second bandwidth by using different control channel
configurations in at least one neighboring cell, the first
bandwidth being greater than the second bandwidth.
As for further refinements of the apparatuses according to an
example of the present invention, the first carrier signal may be a
long term evolution carrier signal, and the second carrier signal
may be a global system for mobile communications carrier signal. In
addition, the transforming from time domain into frequency domain
may be a (fast) Fourier transformation, and the transforming from
frequency domain into time domain may be an inverse (fast) Fourier
transformation. Still further, the timing information may an
orthogonal frequency division multiplexing guard interval, and the
channel information may channel state information. Moreover, the
queuing may be performed based on a first in first out queue.
Finally, there may be a single means for transmitting or a
plurality of means for transmitting in a coordinated manner.
Furthermore, at least one of, or more of means for accommodating
203, means for transmitting 2011; 2011', means for subtracting
2019, means for filtering 2013; 2026; 2021b, means for calculating
2015, means for combining 2018, means for transforming 2014; 2016,
means for inserting 2017, means for retrieving 2021, means for
receiving 2023, means for generating 2022, means for queuing 2027,
means for modulating 2025; 2012, means for demodulating 2024, means
for decoding 2021a, means for detecting 2021c, means for extracting
2021d, means for estimating 2021e, means for processing 2021f,
means for distributing and/or the transmitter 201'/transmitter
201/receiver 202, or the respective functionalities carried out,
may be implemented as a chipset or module.
The present invention also relates to a system which may comprise
the above-described transmitter 201 (or transmitter 201' in
conjunction with accommodator 203), the receiver 202 and the
above-mentioned distributor.
Without being restricted to the details following in this section,
the embodiment of the present invention may be summarized as
follows: The invention resides in
1. the idea of efficient Combined Transmission of two (or more)
radio access technologies (RAT) in a single frequency block, i.e.,
a narrowband system and a wideband system, by
maintaining a single wideband (LTE) carrier (surrounding the
narrowband (GSM) carrier(s) in frequency domain), and
Not introducing explicit (GSM-to-LTE frequency) guard bands.
Combined Transmission may be the transmission from
a. a single RF, power amplifier, and antenna chain, or
b. multiple RF, power amplifier, and antenna chains in a
coordinated manner.
2. A Pre-coding Solution on the transmitter side for counter-acting
the interference caused by the narrowband system (GSM) into the
wideband system (LTE).
3. In a delay reduction method for serial interference cancellation
used on the receiver side for counter-acting the interference
caused by the narrowband system (GSM) into the wideband system
(LTE).
4. In distributing via network planning different LTE Release 8
control channel configurations over the network in such a way that
a significant part or even a complete GSM network can be embedded
into e.g. a 20 MHz carrier LTE Release 8 network.
Feasibility of Invention:
Using Combined Transmission of GSM and LTE, the performance of LTE
both of the data and the control channels may be affected. Receiver
interference cancellation and transmitter pre-coding intend to
reduce drastically the performance degradation.
1. Combined Transmission of GSM and LTE:
The principle of Combined Transmission of a narrowband carrier and
a wideband carrier is illustrated in FIG. 3 using the example of
Combined Transmission of GSM and LTE Release 8.
2. Pre-coding Solution for Combined Transmission of GSM and
LTE:
One option is to apply a pre-compensation according to FIG. 4,
where the effective interference from the GMSK signal to each
subcarrier of the LTE signals may be pre-subtracted. For that
purpose the GMSK signal is transformed from the time into the
frequency domain by the same FFT (fast Fourier transformation) as
may be used at the LTE receiver for the LTE signal. Those
subcarriers located at the transmission of the GMSK signal are
filtered out before subtraction of the interfering signals per each
subcarrier of the LTE signal.
The SC filter in FIG. 4 has a functionality for calculating the
resulting distortion from the GSM to the LTE signal, taking the
OFDM GI as well as CSI information of the radio channels into
account. In case of a combined transmission from a single power
amplifier and antenna location, common channel estimation may be
applied. In case of two different locations for the GSM and LTE
transmission, the CSI estimation of the GSM signal may be
transferred to the LTE processing unit.
In FIG. 5, the LTE OFDM signal and the GMSK signal is drawn above
each other. It can be seen that the symbol length of GMSK signals
and the LTE OFDM signal have different length and that the OFDM
signal has a GI, while GMSK has none. Due to shorter symbol length
of the GMSK signal, there may result interference as a composition
of several GMSK symbols. This may be quite severe and spread over
the full frequency band as the length of the OFDM symbol is not a
multiple of the GMSK symbol length.
In case that there is a frequency selective radio channel with
different multipath components, the resulting GSM to LTE
interference may be different, as the GMSK signal has no GI and has
a shorter symbol length. For this reason, in case of frequency
selective radio channels, the transmitter may be provided with full
channel information for proper pre-distortion as explained
above.
In the discussion of closed loop cooperative MIMO (multiple input
multiple output), an extended feedback of CSI is considered which
may be used for pre-distortion as well.
It is also possible to use the GSM frequency resources for LTE in
case the GSM carrier is not allocated (gain per not transmitted
TDMA frame in best case e.g. 5 ms, in worst case e.g. 4 ms).
3. Delay Reduction in Interference Cancellation for Receiver
Solution to Combined GSM and LTE
For the time domain approach in FIG. 6, the signal separation may
be done at the receiver side. For this purpose, it is exploited
that an interferer with a much larger Rx power than the desired
signal may be easily detected and decoded and afterwards subtracted
from the weaker signal. The reason is that the small user signal
may not degrade detection of the strong signal significantly. For
this reason, the receiver may have two branches. The upper one is
for the demodulation of the GMSK signal as used for GSM. The
demodulated and decoded signal is than used to generate a replica
of the originally transmitted GSM signal including a copy of the
low-pass filter (LPF). This signal is than subtracted from the
receive signal in the lower LTE branch, thereby subtracting the GSM
to LTE interference.
The FIFO (first in first out queue) in FIG. 6 may be included for
compensation of the processing delay in the GSM branch. Afterwards,
an FFT can be performed on the interference free Rx signal.
The GSM carrier bandwidth may be quite low with e.g. only 200 KHz
so that it might be quite often frequency flat. Otherwise, the
frequency selectivity of the radio channel may have to be
replicated in the receiver as well before subtracting of the
interfering GMSK signal, based on according channel estimation.
IF (interference) cancellation is proposed for two different
systems. While GSM may have a frame length of 20 ms, for LTE
Release 8, a very short sub frame length of 1 ms may reduce the
latency on the radio air interface.
Optionally, the GSM signal may be channel decoded. As the LTE
decoding may take place e.g. after cancellation of the GSM signal,
the LTE signal may be delayed by the total processing duration of
the GSM processing chain.
It is proposed to use CSI estimation for the GSM signal from the
frames before, which will render an estimate.
The received signal {right arrow over (Y)}={right arrow over
(X)}.sub.LTE{right arrow over (H)}.sub.LTE+{right arrow over
(X)}.sub.GSM{right arrow over (H)}.sub.GSM can be represented by a
Toeplitz matrix {right arrow over (Y)} and is composed of a LTE
signal part {right arrow over (X)}.sub.LTE and an interfering GSM
data part multiplied by the corresponding channel impulse responses
for LTE signal part {right arrow over (h)}.sub.LTE and interferer
{right arrow over (h)}.sub.GSM. The received symbols are
transformed by the IC algorithm, which can be expressed by a
multiplication of the received data matrix {right arrow over (Y)}
by the filter weighting vector {right arrow over (a)}. This is
resulting in {right arrow over (Z)}={right arrow over (Y)}{right
arrow over (a)}={right arrow over (X)}.sub.LTE{right arrow over
(H)}.sub.LTE{right arrow over (a)}+{right arrow over
(X)}.sub.GSM{right arrow over (H)}.sub.GSM{right arrow over
(a)}
The filter weighting vector {right arrow over (a)} must fulfill the
properties {right arrow over (H)}.sub.GSM{right arrow over (a)}=0;
{right arrow over (a)}.noteq.0; {right arrow over
(H)}.sub.LTE{right arrow over (a)}.noteq.0
The filter weighting vector is estimated based on the CSI received
in the last GSM burst periods, prior to the current LTE sub frame.
Since LTE sub frame duration of 1 ms is not a multiple of GSM burst
duration of 577 .mu.s, the update of the IC filter configuration
may happen asynchronous to the LTE sub frame periods. Averaging
might be applied to get a more reliable CSI of the multiple user
signals of the last burst durations.
In this way, the delay in the LTE processing chain may be limited
to the processing duration of a FIR (finite impulse response)
filter which might require a depth of approximately 4 GMSK symbol
periods corresponding to approximately 16 .mu.s.
4. Distributing via network planning different LTE Release 8
control channel configurations over the network in such a way that
a significant part or even a complete GSM network can be
embedded:
In an LTE Release 8 system with a very low number of users per
cell, the PDCCH (physical downlink control channel) and the PHICH
(physical hybrid automatic repeat request indicator channel)
control channels are rather scarcely populated, such that empty
Resource Element Groups or Physical Resource Blocks can be
identified for embedding narrowband (GSM) carrier(s).
Using network planning to distribute different control channel
configurations and optimizations over neighbor cells allows for
creating sufficient options for embedding a significant part or a
complete e.g. GSM network in a Reuse 1 LTE Release 8 network.
The example illustrated in FIG. 9 shows actual narrowband (GSM)
embedding regions for a single configuration as well as potential
narrowband (GSM) embedding regions due to other configurations e.g.
for 10 MHz. The narrowband embedding region for a single 10 MHz
configuration with medium number of scheduled users offers 2.6 MHz
frequency spectrum. A 20 MHz carrier with a similar load and
appropriately optimized may offer about a twice as large narrowband
embedding region per configuration. By varying control channel
configuration and optimization, the union set of narrowband
embedding regions will offer sufficient spectrum for embedding a
typical 2.times.2.times.2-Sites GSM network.
Further Examples
For the purpose of the present invention as described herein above,
it should be noted that
an access technology may be any technology by means of which a user
equipment can access an access network (or base station,
respectively). Any present or future technology, such as WiMAX
(Worldwide Interoperability for Microwave Access) or WLAN (Wireless
Local Access Network), BlueTooth, Infrared, and the like may be
used; although the above technologies are mostly wireless access
technologies, e.g. in different radio spectra, access technology in
the sense of the present invention may also imply wirebound
technologies, e.g. IP based access technologies like cable networks
or fixed line.
a network may be any device, unit or means by which a station
entity or other user equipment may connect to and/or utilize
services offered by the access network; such services include,
among others, data and/or (audio-) visual communication, data
download etc.;
generally, the present invention may be applicable in those
network/user equipment environments relying on a data packet based
transmission scheme according to which data are transmitted in data
packets and which are, for example, based on the Internet Protocol
IP. The present invention is, however, not limited thereto, and any
other present or future IP or mobile IP (MIP) version, or, more
generally, a protocol following similar principles as (M)IPv4/6, is
also applicable;
a user equipment may be any device, unit or means by which a system
user may experience services from an access network;
method steps likely to be implemented as software code portions and
being run using a processor at a network element or terminal (as
examples of devices, apparatuses and/or modules thereof, or as
examples of entities including apparatuses and/or modules
therefore), are software code independent and can be specified
using any known or future developed programming language as long as
the functionality defined by the method steps is preserved;
generally, any method step is suitable to be implemented as
software or by hardware without changing the idea of the invention
in terms of the functionality implemented;
method steps and/or devices, units or means likely to be
implemented as hardware components at the transmitter and/or
receiver, or any module(s) thereof, are hardware independent and
can be implemented using any known or future developed hardware
technology or any hybrids of these, such as MOS (Metal Oxide
Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS),
BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL
(Transistor-Transistor Logic), etc., using for example ASIC
(Application Specific IC (Integrated Circuit)) components, FPGA
(Field-programmable Gate Arrays) components, CPLD (Complex
Programmable Logic Device) components or DSP (Digital Signal
Processor) components; in addition, any method steps and/or
devices, units or means likely to be implemented as software
components may alternatively be based on any security architecture
capable e.g. of authentication, authorization, keying and/or
traffic protection;
devices, units or means (e.g. transmitter and/or receiver, or any
one of their respective means) can be implemented as individual
devices, units or means, but this does not exclude that they are
implemented in a distributed fashion throughout the system, as long
as the functionality of the device, unit or means is preserved;
an apparatus may be represented by a semiconductor chip, a chipset,
or a (hardware) module comprising such chip or chipset; this,
however, does not exclude the possibility that a functionality of
an apparatus or module, instead of being hardware implemented, be
implemented as software in a (software) module such as a computer
program or a computer program product comprising executable
software code portions for execution/being run on a processor;
a device may be regarded as an apparatus or as an assembly of more
than one apparatus, whether functionally in cooperation with each
other or functionally independently of each other but in a same
device housing, for example.
Although the present invention has been described herein before
with reference to particular embodiments thereof, the present
invention is not limited thereto and various modification can be
made thereto.
For ease of clarity, the following table provides a survey of the
abbreviations used in the above description. It is to be noted that
an "s" following an abbreviation represents the plural of that
abbreviation, e.g. "GIs" represents "guard intervals".
TABLE-US-00001 3GPP: 3.sup.rd generation partner ship project LTE:
Long term evolution A&F: amplify and forward BS: base station
CDD: cyclic delay diversity CSI: channel state information D&F:
decode and forward DL: downlink FDD: frequency division duplexing
GI: guard interval HARQ: hybrid automatic repeat request LOS: line
of sight MS: mobile station MCS: modulation and coding scheme MIMO:
multiple input multiple output NB: Node B OFDM: orthogonal
frequency division multiplexing OFDMA: orthogonal frequency
division multiple access R8: Release 8 RN: relay node RS: reference
signal RB: resource block SC: subcarrier TDM: time domain
multiplexing UE: User equipment UL: uplink
* * * * *